Process of making printing-plates



E. LEITNER.

PROCESS 0F MAKING PRINTING PLATES.

APPLICATION FILED FEB. I0. I9I4.

1,329,088. Patented Jan. 27, 1920.

f l. 73%7 l 7 Syvum/vtm: mz'ZeiZ//er UNITED sTATEs PATENT oEEIcE. l

EMIL LEITNER, OF HOBOKEN, NEW JERSEY, ASSIGNOR TO POWERS PHOTO ENGRAVING COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK. l

PROCESS OF IVIAKING PRINTING-PLATES.

Specification of Letters Patent.

Patented Jan. 27, 1920.

Application led February 101914. Serial No. 817,914.

esses for producing by chemical and vmechanical means a deep etched plate.

Objects of the invention are to provide photo-mechanically a printing plate which is deep etched without sacrificingl or weakening the half-tone dots therein, and without marring the gradation of color tones therein; to produce entirely by mechanical. means a plate in which the top or upper portions of the half-tone dots or like figures are preserved intact as to area, while securing a deep etch or depression of the sur-rounding portions of the plate. These and other ob- -jects of the invention will be set forth hereinafter in part, and in part will be obvious.

The invention consists in the novel steps, processes, combinations and improvements herein indicated and described.

The accompanying drawings represent d-iagrammatically and on a highly magnified scale certain steps in the process. Figure l represents the plate after the first etch; Fig. 2 represents the plate with the protective covering l applied to the faces and sides of the screen figure preparatory to the deep etch; and Fig. 3 represents the plate after the deep etch.

In carrying out my process, the preliminary steps in making a half-tone plate may be performed in the usual manner. An original may be placed before the camera, and a negative made therefroinwith the interposition of the half-tone -screen prod-ucing the usual 'stippled or half-tone negative.

A copper plate, or other like plate, is sensitized in a suitable manner, as by having applied to its surface a solution of albumin mixed with a light sensitive agent, such as ammonium bichromate. This solution is spread in a uniform layer over the surface of the plate and dried as a coating thereon in a suitable manner as by whirling the plate over a heater.

The sensitized surface of the plate is then exposed to .light action beneath the halftone negative, and is afterward developed in water. in case of the enameled top plate, it is then heated and the enamel burnt in. The plate is then given its first etch in the usual manner, preferably with ,ferrie chlorid solution.-

After theplate has been so developed and etched, its surface is broken up into a great' number of dots or like screen figures, by the action of the'half-tone screen in a wellknown manner. I apply an acid resistant material .to the tops or faces of the dots or screen figures, and also tothe upper part of the sides thereof.4 For this purpose, I roll up the plate with a mixture of printers ink with tar oil, using preferably a jobbing ink, such for example as Helmuths job After drying the developed plate,

black Z. W. grinding, using or mixing the S ink and oil in substantially the proportions 'of one part of the oil to from three to four parts of the ink. After the ink and oil have been thoroughly and uniformly mixed together, I roll up the plate therewith.- In rolling up the plate I use ayvroller made of the ordinary inking roller composition mounted in bearings to turn easily instead of the ordinary hard leather covered rolling up roller. By the use of the resilient composition roller t'heindividual dots depress its surface and the ink is thus carried down the sides of the dots. The rolling is continued untilthe ink not only covers the top or surface of the dots, or like half-tone figures, but goes down the sides thereof to a distance substantially half-way of the depth of the depressions as left by the first etch.

After the ink has been so put on, I apply to the plate, the acid resistant material, using preferably asphaltum powder, which powder is applied uniformly over the plate. The loose powder is removed from the uninked portions of the plate, in a suitable manner as by gentle brushing with a soft brush or with a powder puff.

The asphaltum powder remaining adherent upon the inked portions of the plate is heated or burned so as to melt the powder and cause it to run together to form a proper acid resistant coating over the ink. The burning or melting of the powder is regulated so as to avoid melting the ink and thereby causing it to run down farther along the sides of the half-tone dots or figures.

The plate so protected by its acid resistant coating, I etch with a deep etch, such as iron perchlorid, and by reason of both the top and the upper portion of the sides of the half-tone dots or like figures being protected by the resist, the deep etching acts onlyin the depressions between `said dots or hke screen figures, without affecting the to and upper portion of the sides thereof, t at is yvlthout decreasing the size of the printing surface or area of the dots or like screen figures and thusv without impair-ing or vary'- y ing the relative tones of the plate. Thisgives an excellent printing plate adapted for use with many ing papers, printing more easily, requiring very little make-ready or other preliminary preparations, and making an exceedingly useful and excellent printing plate under widely varying conditions of use.

In the drawings 5 designates the body of a plate and 6 the dots thereon, 7 the protecting covering of ink applied as described after the first etch which extends over the top of each dot and approximately half way down the sides thereof. 8 indicates the part cut away by the second etch effected While the top and sides of the dots are protected.

It will be understood that variations from the herein described steps may be made, Within the scope of the accompanying claims, Without. departing from the principles of the invention and without sacriicing its chief advantages.

What I claim as my invention and desire to secure by Letters Patent is l. The process of deep etching a plate having a half tone design etched thereon in which the dotsof the design have the tone values of. the original, which process consists in applying a protecting covering to different klnds of printboth the top andthe upper portions only of the sides of the dots etch, and deep etching the low unprotected places between the dots, whereby the relative tonevalues of all parts of the plate are maintained. by theprevention of the diminution in size of the dots during the deep etching.

2. The. process of deep etching a plate having a half tone design etched thereon in which the dots of the design have the tone values of the original, which prof-ess con sists in applying a covering consisting of a mixture of printers ink and tar oil o both the top and the upper portions only of the .sldes of the dotsformed by the iirst etch,

dusting the plate with acid resist powder, and deep-etching the 10W unprotected places betweenthe dots, whereby the relative tone values of all parts of the plate are maintained by the prevention of the diminution in size of the dots during the deep etching. 3. The process of deep etching a plate having a half tone design etched thereon in which the dots of the design have the tone values of the original, which process consists in applying a covering consisting of a mixture of printers ink and tar oil to both the top and the upper portions only of the sides of lthe dots formed by the first etch, dusting the plate with asphaltum, heating the plate and deep-etching the low unprotected places bet-Ween the dots, whereby therelative tone values of all parts of the plate are maintained by the prevention of the diminution in'size of the dots during the deep etching. In testimony whereof, I have signed my name to this specification, in the presence of two subscribing witnesses.

EMIL LEITNER. Witnesses:

JOHN D. MORGAN, JOHN W. SNYDER.

formed by the first 

